The present invention relates to a semiconductor device, and more particularly, to a semiconductor device capable of functioning as a solid-state image pickup device that reads pixels on an individual column basis.
It has been known that there is a method of enabling a solid-state image pickup device (image sensor) to perform a high-speed read operation.
A solid-state image sensing device described, for instance, in Japanese Unexamined Patent Application Publication No. 2008-022259 includes a pixel signal read line, a pixel section, and a pixel signal read section. The pixel section has an array of pixels including a photoelectric conversion element. The pixel signal read section reads a pixel signal from the pixel section through the pixel signal read line. The pixel signal read section includes a current source circuit including a load element that acts as a current source coupled to the pixel signal read line to form a source follower. The current source circuit includes a circuit that causes a current flow in accordance with a slew rate of the pixel signal read line and permits the current source to cause a current flow accordingly.
A solid-state image sensing device described, for instance, in Japanese Unexamined Patent Application Publication No. 2011-234243 includes a photoelectric conversion means and a diffusion region. The photoelectric conversion means stores a photo-charge for a plurality of pixels disposed in an imaging section in accordance with the amount of received light. The diffusion region is used to extract a signal corresponding to the photo-charge stored in the photoelectric conversion means. This solid-state image sensing device further includes a transfer transistor, an amplifying transistor, a signal line, and a current source. The transfer transistor transfers the photo-charge in the photoelectric conversion means to the diffusion region. The amplifying transistor is coupled to the diffusion region. The signal line is coupled to the output side of the amplifying transistor. The current source is coupled to the signal line. At least one transistor for controlling the output waveform of the amplifying transistor is coupled to the current source.